Bug 2025101 (CVE-2021-4090)

Summary:	CVE-2021-4090 kernel: Overflow of bmval[bmlen-1] in nfsd4_decode_bitmap function
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bdettelb, bhu, bskeggs, carnil, chwhite, crwood, dhoward, dvlasenk, hdegoede, hkrzesin, jarod, jarodwilson, jburrell, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, nmurray, ptalbert, qzhao, rkeshri, rvrbovsk, steved, vkumar, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.16 rc2	Doc Type:	If docs needed, set a value
Doc Text:	An out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel. Missing sanity may lead to a write beyond bmval[bmlen-1] in nfsd4_decode_bitmap4 in fs/nfsd/nfs4xdr.c. In this flaw, a local attacker with user privilege may gain access to out-of-bounds memory, leading to a system integrity and confidentiality threat.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-03-16 13:58:46 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2037043, 2049200
Bug Blocks:	2025102, 2031058

Description Pedro Sampaio 2021-11-19 20:57:11 UTC

An out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel. Missing sanity may lead to a write beyond bmval[bmlen-1] in nfsd4_decode_bitmap4 in fs/nfsd/nfs4xdr.c. 

In this flaw, a local attacker with user privilege may gain access to out-of-bounds memory, and write leading to a system integrity and confidentiality threat.

Upstream discussion:

https://lore.kernel.org/linux-nfs/97860.1636837122@crash.local/
https://lore.kernel.org/linux-nfs/163692036074.16710.5678362976688977923.stgit@klimt.1015granger.net/

Comment 11 Product Security DevOps Team 2023-03-16 13:58:42 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-4090